Exam 2 - all CNs Flashcards
Vagus Nerve: function of the terminal ganglia
Terminal ganglia close to target tissues
- innervated by the vagus nerve are the parasympathetic efferents relay ganglia
inspiratory stridor means
high pitched sound during inspiration
Facial Nerve
nucleus associated with general sensory functional class
Nucleus of spinal tract of V
General Sensory Functions
Tactile sensations from
- skin of external ear,
- wall of external auditory meatus &
- outer surface of tympanic membrane
Bell’s Palsy:
prevalence
cause
acute or gradual onset?
characterized by (3)
- The most common disease affecting facial nerve
- •Often caused by herpes simplex virus
- •Acute onset
- •Characterized by
- paralysis of facial muscles,
- impaired corneal blink reflex, and
- hyperacusis
Bell’s Palsy is Most common disease affecting facial nerve and Often caused by herpes simplex virus. It has an Acute onset and is Characterized by paralysis of facial muscles, impaired corneal blink reflex, and hyperacusis (inability to tolerate normal sounds which seem abnormally loud)
action of inferior rectus muscle:
depression of the eye
where are the nuclei that serve the glossopharyngeal nerve?
Rostral Medulla
What foramen does the glossopharyngeal nerve pass through in the cranium?
The Glossopharyngeal nerve passes out of the cranium through the jugular foramen
(the superior and inferoir ganglia are also in the jugular foramen)
Whare are the nuclei that serve the vagus nerve located?
the medulla
what primary afferents ore the only CN V afferents that do not have their cell bodies in the trigeminal ganglion?
the 1° afferent cell bodies for proprioceptive information from muscles of mastication.
they synapse in the Mesencephalic Nucleus of the midbrain and rostral pons
Clinical evaluation of the Vestibulocochlear Nerve includes tests of: (3)
- –Ability to coordinate eye–head movements (vestibulo-ocular reflex)
- –Balance tasks
- –Hearing
Clinical evaluation of the vestibulocochlear nerve includes tests of: Ability to perform coordinated eye–head movements with movement of the head (vestibulo-ocular reflex), balance tasks and demonstrate appropriate hearing. We will discuss all of these test when we discuss the vestibular and auditory systems later in the course
RIN
Rostral Interstitial Nucleus
(of the midbrain reticular formation)
PPRF
Paramedian Pontine Reticular Formation
what does the abducens nerve innervate?
lateral rectus muscle
Glossopharyngeal nerve: where are the otic ganglion found?
suspended from mandibular nerve immediately below foramen ovale
list the types of functions carried in the vagus nerve:
- –General sensory
- –Special sensory
- –Branchial motor
- –Visceral motor
- –Visceral sensory (left off this diagram)
(the same 5 functions as the glossopharyngeal nerve)
Where is horizontal gaze coordinated?
Paramedian pontine reticular formation
CN number of Abducens Nerve
VI
Inferior rectus
Innervation:
primary action:
Innervation: Oculomotor (III)
primary action: depression
List the cranial nerve nuclei in pons and medulla related to the facial nerve (VII): (4)
Facial Nucleus
Solitary nucleus
Superior salivatory nucleus
Nucleus of the spinal tract of V
special sensory functions of vestibulocochlear nerve
- Vestibular information
- balance/equilibrium
- Cochlear information
- hearing/auditory
The vestibulocochlear nerve (CN VIII) Special sensory conveys Vestibular (balance/equilibrium) information from the vestibular organs of the inner ear and Cochlear (hearing/auditory) information also from the inner ear
Nucleus oralis:
location
transmits
one of three regions of spinal trigeminal nucleus
- Most rostral
- Transmits
- fine (discriminative) orofacial touch
what muscles should we palpate in clinical evaluation of the trigeminal nerve & locations?
what should we do while palpating?
–Masseter (A)
–Temporalis (B)
–Pterygoid (C)
have pt resist jaw opening during palpation
Glossopharangeal Nerve (IX): what is the purpose of the special sensory component?
–Special sensory – taste from the posterior one-third of the tongue
What is the pyriform cortex composed of?
The pyriform cortex is composed of the:
- Periamygdaloid cortex
- Anterior portion of parahippocampal gyrus ()
it is the primary olfactory cortex and locaed in the medial temporal lobe
meaning of dysarthria
hoarseness of speech
four steps in the initial portion of the primary pathway that starts with Olfactory mucosa:
- The surface of the olfactory mucosa is covered in mucus
- Sensory cells (bipolar) are imbedded in the mucus
- Axons from the sensory neurons collectively form the olfactory nerve & penetrate the cribriform plate of ethmoid bone
- The axons end on the mitral cells of the olfactory bulb
The receptor surface is the Olfactory mucosa which is Mucus covered. Sensory cells imbedded in mucus. Axons from these sensory cells collectively form olfactory nerve & each penetrates the cribriform plate of ethmoid bone. These axons End on mitral cells of olfactory bulb
There are olfactory tract projections to the following 6 cortical areas:
- Hypothalamus
- Orbitofrontal cortex
- Amygdala
- Hippocampus - (strong memories with odors)
- dorsomedial nucleus of thalamus (not shown)
- Limbic structures - (strong emotional reactions to odors)
Brainstem gaze centers:
function (general)
location
Function
- Coordination of conjugate eye movement
–Located in:
- Paramedian pontine reticular formation (PPRF)
- Rostral interstitial nucleus (RIN) of the midbrain reticular formation
What does the Ophthalmic nerve pass through when entering the scull?
Superior Orbital fissure
How are the axons leaving the trochlear nucleaus unqiue? (2)
- they decussate and innervate the contralateral superior oblique muscle
- Trochlear nerve is the only cranial nerve to exit the dorsum of the brainstem
Glossopharyngeal nerve (IX): What is the general sensory function?
–General sensory –
tactile sensation from the tonsils, the pharynx, the middle ear and the posterior 1/3 of the tongue
What type of functions does vestibulocochlear nerve have?
special sensory
Olfactory G-protein receptor cells:
receptor activation
- G-protein activates adenylate cyclase and cAMP production
- cAMP 0pens ion channels in the cell membrane, resulting in Na+ & Ca++ influx & Cl- efflux
- This causes depolarization- AP generation
Olfactory Receptor activation produces G-protein activation of adenylate cyclase and cyclic AMP production. The cyclic AMP Opens ion channels in the cell membrane, resulting in Na+ & Ca++ influx & Cl- efflux – the resulting influx of positive ions and efflux of negative ions produces a Depolarization and action potential generation
Glossopharyngeal nerve: what type of neurons does the nucleus ambigous have?
somatic motor: lower motor neurons which innervates the stylopharyngeus muscle
how can you clinically evaluate the integrity of the accessory nerve?
its integrity is tested using manual muscle testing against resisted
- head turning and
- shoulders shrugging
what is the spinal trigeminal tract?
first degree afferent axons from CN V that go either ascending or descending to 2nd degree neurons in the: nucleus of the spinal tract of V (spinal trigeminal nucleus)
(the words under Dr. Lake’s powerpoint says it could be to the mesencephalic trigeminal nucleus, or the cheif trigeminal nucleus too, but that is not what other sources say. I also emailed Dr. Lake and he replied that it is just the spinal trigeminal nucleus!)
where are the nuclei that serve the Accesory Nerve located?
- Medulla–
- Nucleus ambiguus
- Cervical Spinal Cord–
- Cervical ventral horn
The cranial portion arises from the Nucleus ambiguus of the medulla and the spinal portion arises from motor neurons of the upper Cervical ventral horn. The Cervical ventral roots rise through the foramen magnum to join with the cranial portion.
Together both portions exits thru jugular foramen
sensory test for fine touch and pin prick to face
will be discussed later with somatosensory systems
Inferior Oblique
Innervation:
primary action:
Innervation: Oculomotor (III)
primary action: Extorsion
list the functions of the visceral motor portion of the Vagus Nerve:
Visceral motor includes the
- parasympathetic innervation of the organs of the Thoracic & abdominal viscera
how does a jaw jerk reflex test work?
what are the afferent & efferent limbs?
what nuclei are invovled in the reflex?
- tapping of the jaw produces reflex contraction of the muscles of mastication
- –Afferent & efferent limb mandibular V3
- –Both thru mesencephalic & motor nucleus of V
The three most common sources of injury to the Oculomotor nerve (CN III) or Trochlear nerve (CN IV)
- –Inflammation of meninges
- –Aneurysms of internal carotid artery or other circle of Willis arteries
- –Swelling in brain with increased venous pressure in cavernous sinus
what nucleus gives rise to our sensation of jaw poistion and is the afferent limb in reflexes like the jaw jerk reflex?
Mesencephalic Nucleus of the midbain and rostral pons
Vagus Nerve: function of nucleus soitarius
–Nucleus solitarius –
visceral sensory afferents
definition of branchial
Medical Definition of BRANCHIAL. : of or relating to the gills or to parts of the body derived from the embryonic branchial arches and clefts.
function of the lateral rectus muscle
ocular (eye) abduction
(hence name “abduc - ens”)
what is the nuclear complex or nucleus serving the abducens nerve?
Abducens nucleus
(located in caudal pons)
How many extraocular muscles are there?
6
What is the complex and/or nuclei that serve the trochlear nerve?
Trochlear nucleus
in midbrain caudal to oculomotor complex
Is there just one spot in the brain that will affect conjugate eye movement if damaged?
No. loss of conjugate eye movement can result from damage to more than one brain region.
Function of superior oblque muscle:
intorsion (medial rotation)
what is the pyriform area?
primary olfactory cortex of medial temporal lobe – pyriform area
. where the axons of the mitral cells primarily end
What makes up the oculomotor nuclear complex? (2)
- Oculomotor nucleus (LMN with somatic motor function)
- Edinger-Westphal nucleus (parasympathetic prganglionic neurons with visceral motor function)
what does olfactory projections to the hippocampus do?
Hippocampus – strong memories with odors
what is the difference between nociception and pain?
Physiologists distinguish between pain and nociception; where
- nociception refers to signals arriving in the central nervous system resulting from activation of specialized sensory receptors called nociceptors that provide information about tissue damage.
- Pain then is the unpleasant emotional experience that usually accompanies nociception.
http://cell.uchc.edu/pdf/fein/nociceptors_fein_2012.pdf
What is conjugate movement?
- Coordinated movment of the eyes to maintain normal vision
- Requires cooperation of different CNs
- Eyes move together with great precision
Vagus Nerve: function of the Spinal Nucleus of V
–Spinal Nucleus of V –
somatic sensory (somatosensory afferents)
what are the parasympathetic nuclei of the brainstem that olfactory projections go to
the parasympathetic nuclei of brainstem
- Superior & inferior salivatory nuclei – salivation to pleasant odors
- Dorsal motor nucleus of vagus – nausea and vomiting to unpleasant odors
Projections to the Hypothalamalamic neurons which in turn have projections to parasympathetic nuclei of brainstem. Projections to the Superior & inferior salivatory nuclei – salivation to pleasant odors and to the Dorsal motor nucleus of vagus – nausea and vomiting to unpleasant odors
What is the purpose of the visceral motor component of the glossopharyngeal nerve (IX)?
–Visceral motor – parasympathetic innervation of the parotid gland (preganglionic to otic ganglion)
describe the Palthway of the nerve branches of facial nerve
- –Full nerve leaves pontomedullary junction
- –It Passes thru internal acoustic meatus with CN VIII
- –then Enters facial canal where geniculate ganglion found
- –the Parasympathetic fibers then split off to form greater petrosal nerve and synapse in pterygo-palatine ganglion in the pterygo-palatine fossa
- –the Sensory & motor branches pass thru stylomastoid foramen
The specific path of the facial nerve involves the Full nerve leaving the brainstem at the pontomedullary junction and passing thru internal acoustic meatus with CN VIII to Enter the facial canal where geniculate ganglion is found.
Parasympathetic fibers then split off to form the greater petrosal nerve which synapse in pterygo-palatine ganglion in the pterygo-palatine fossa
General sensory & motor branches pass through stylomastoid foramen
action of superior rectus muscle:
elevation of eye
What does the hypglossal nerve innervate?
the intrinsic & extrinsic tongue muscles
action of medial rectus muscle:
adduction of eye
two things commonly tested in clinical evaluation of the facial nerve
- •Special sensory –
- taste (salty, sweet or sour)
- •Branchial motor
- –Make facial expressions
- –Observe for asymmetries
Facial nerve: What nucleus is associated with the special sensory functions
gustatory division of the solitary nucleus
What does the trochlear nerve innervate?
superior oblique muscle
what is the only division of the trigeminal nerve that contains motor function?
Mandibular (V3)
Glossopharyngeal nerve (IX): superior ganglion contains what kind of cell bodies?
–Superior ganglion –
somatic afferents (cell bodies of somatic primary afferent fibers)
meaning of dysphagia
Difficulty with swallowing
Movment of eyes to right requires the activation of which muscles?
left medial rectus (oculomotor nerve, III)
right lateral rectus (abducens nerve, VI)
Vagus Nerve: function of the inferior ganglion
Inferior ganglion –
- visceral & special sensory afferents
action of inferior oblique muscle:
extorsion (lateral rotation)
Facial nerve number
CN VII
name of cranial nerve I:
olfactory nerve
nucleus caudalis:
location
Transmits
one of three regions of spinal trigeminal nucleus
- Most caudal
- transmits:
- orofacial nociception
- thermal sensations
draw the facial nerve chart
what is the number for the Glossopharyngeal Nerve?
IX
Glossopharyngeal nerve (IX): Inferior ganglion contains what kind of cell bodies?
–Inferior ganglion –
visceral & special sensory (cell bodies of the visceral & special sensory primary afferent fibers)
what type of function does the Abducens Nerve have?
Somatic Motor
What cranial nerves innervate the extra-ocular muscles?
III (somatic motor component)
IV
VI
Oculomotor (III)
Trochlear (IV)
Abducens (VI)
Where is vertical gaze controlled?
Rostral interstitial nucleus (RIN)
What Connects the PPRF and RIN to oculomotor lower motor nuclei?
Ascending medial longitudinal fasciculus (MLF)
Clinical Evaluation of the Facial Nerve: Special sensory
taste with one or more of the following:
- salty
- sweet
- sour
list the nuclei that serve the vagus nerve (4)
- –Nucleus solitarius –
- visceral sensory afferents
- epiglottic taste - gustatory portion
- –Dorsal motor nucleus of X –
- visceral motor preganglionic parasympathetic efferents
- –Spinal Nucleus of V –
- somatic sensory (somatosensory afferents)
- –Nucleus ambiguus –
- branchial motor to the pharyngeal and laryngeal musculature
Glossopharyngeal nerve: what type of neurons does the Inferior salivatory nucleus have?
parasympathetic preganglionic neurons which end in the otic ganglion
what is used as a sign of function for the clinical evaluation of the glossopharyngeal nerve?
- The gag reflex is used as sign of function of the glossopharyngeal nerve
- but this is somewhat unreliable as pharyngeal wall innervated by both glossopharyngeal and vagus nerves
- however this is not a big problem because isolated lesions of the glossopharyngeal nerve are rare.
Clinical Evaluation of the Olfactory Nerve
- •Evaluation of sense of smell - test each nostril separately with a familiar scent
- •Anosmia (inability to smell) may occur with
- –Common cold
- –Trauma to face
- –Some degenerative diseases such as Parkinson’s and Alzheimer’s
- –Predict death?
Clinical evaluation of the olfactory nerve involves Evaluation of sense of smell - test each nostril separately with a familiar scent
Anosmia (inability to smell) may occur with Common cold, with Trauma to face and some degenerative diseases such as Parkinson’s and Alzheimer’s. There was a study published in October of last year which reported that adults aged 57 or above who could not correctly identify five particular scents – peppermint, fish, orange, rose and leather – were more than three times as likely to die in the next five years as those who could smell those odors. This loss of olfactory sensation is a sign of more serious undiagnosed problems – or it means that you can see the grim reaper coming but cannot smell it coming
Which systems (I think this means pathways) project to the Ventral Posteromedial nucleus of the thalamus (VPM)
Powerpoint said “both systems” after describing the medial lemniscal tract and the anterolateral tracts, so I think it is the following
- Medial lemniscus system
- Anterolateral System
Facial nerve: What nucleus is associated with the parasympathetic functions
superior salivatory nucleus
types of function of facial nerve
- –General sensory
- –Special sensory
- –Somatic (Branchial) motor
- –Visceral (Parasympathetic) efferents
Mitral cells
what are they?
what do they form?
where do they end?
–Bipolar neurons within the olfactory bulb
–Axons form the olfactory tract
–Olfactory tract axons end primarily in primary olfactory cortex of medial temporal lobe – pyriform area
Mitral cells are Bipolar neurons within the olfactory bulb and represents the relay ganglion of the olfactory system. Their Axons form the olfactory tract. Olfactory tract axons end primarily in primary olfactory cortex of medial temporal lobe – pyriform area
Tilting the head to the right requires the activation of which extraocular muscles (and neurons) to compensate?
–Tilting head to the right, eyes compensate by torsion to maintain vertical alignment
- §Left extorsion – inferior oblique & oculomotor nucleus (CN III)
- §Right intorsion – superior oblique & trochlear nucleus (CN IV)
Ascending V thalamic pathway
Origin
becomes
–From nucleus interpolaris & nucleus caudalis
–Becomes the head region of the antero-lateral tracts
Vagus Nerve: function of the gustatory portion of the nucleus solitarius
–Gustatory portion of nucleus solitarius –
epiglottic taste
another name for the spinal tract of V
spinal trigeminal nucleus
Cranial nerve nuclei are located (except for 2- which two) *also, Sensory nuclei is more (medial or lateral) and motor is more (medial or lateral)
- Located in the dorsal brainstem (except for CN I and CN II)
- Sensory is lateral
- Motor is medial
bunnies and kitty!
where does the hypothalamus turn projections from the olfactory nerve to?
the parasympathetic nuclei of brainstem
- Superior & inferior salivatory nuclei – salivation to pleasant odors
- Dorsal motor nucleus of vagus – nausea and vomiting to unpleasant odors
Projections to the Hypothalamalamic neurons which in turn have projections to parasympathetic nuclei of brainstem. Projections to the Superior & inferior salivatory nuclei – salivation to pleasant odors and to the Dorsal motor nucleus of vagus – nausea and vomiting to unpleasant odors
What makes the olfactory nerve unique among CNs? (3)
•- It does NOT
- –Synapse in thalamus before reaching cerebral cortex
- –Enter or leave the brainstem directly
- –Have a typical sensory ganglion
- not sure about this one. The powerpoint slide and book says NO typical sensory ganglion, but the text under the slide says it DOES (but this looks added by Dr. Lake maybe by accident?) - Dr. Lake said it DOES in the audio too
Facial Nerve
Parasympathetic innervations
- Lacrimal glands
- Salivary glands
- submandibular
- sublingual
(associated nucleus: superior salivatory nucleus)
what are the three regions of the nucleus of the spinal tract of V?
(the nucleus of the spinal tract of V = spinal trigeminal nucleus)
- Oralis
- Interpolaris
- Caudalis
aphonia
inabillity to give voice
Olfactory receptor cells:
how many?
4 things about them
about 40 million olfactory receptor cells in th enasal mucosa
- has ciliated dendrites imbedded in olfactory mucosa
- –Olfactory receptors are G-protein linked
- –Each receptor cell contains only single type of olfactory receptor
- There are many cells with same type
There are about 40 million Olfactory receptor cells in the nasal mucosa. Each receptor cell has Ciliated dendrites imbedded in olfactory mucosa. Olfactory receptors located on the membranes of the cilia have been classified as a complex type of ligand-gated metabotropic channels, that is Olfactory receptors are G-protein linked. Each receptor cell contains only single type of olfactory receptor. Many cells with same type
What functional types does the glossopharyngeal nerve contain?
- –General sensory –
- tactile sensation from the tonsils, the pharynx, the middle ear and the posterior 1/3 of the tongue
- –Special sensory –
- taste from the posterior one-third of the tongue
- –Visceral sensory -
- fibers from the carotid bodies, carotid sinus
- –Somatic (Branchial motor)-
- innervates stylopharyngeus muscle
- –Visceral motor –
- parasympathetic innervation of the parotid gland (preganglionic to otic ganglion)
For the three sensory divisions of the trigeminal nerve, where are the primary afferent cell bodies found?
and what is it equivilant to?
–Primary afferent cell bodies in in the trigeminal ganglion
(equivalent to DRG)
what is the number for the Trigeminal nerve?
V
Vestibular Nerve:
where do nerve fibers end (I would say begin since it is sensory)?
where are cell bodies?
how does the nerve enter the cranium?
where does nerve enter brainstem
Vestibular portion of the vestibulocochlear nerve
- the nerve Endings are in the ampullae of semicircular canals & macular structures of the inner ear
- found in the petrous portion of the temporal bone
- the Cell bodies are in the vestibular ganglion
- nerve Enters the cranium thru internal acoustic meatus (like auditory nerve)
- nerve enters brainstem at pontomedulary junction (with auditory nerve()
Vestibular nerve portion of the 8th cranial nerve has Endings in ampullae of semicircular canals & macular structures of the inner ear. These structures are in the petrous portion of the temporal bone. The cell bodies of the primary afferent fibers are in the vestibular ganglion and the nerve Enters cranium thru internal acoustic meatus
what is the stylopharyngeus muscle?
stylopharyngeus muscle (anatomy)
On each side of the neck, stylopharyngeus is one of the internal muscles of the pharynx. It arises from the styloid process of the temporal bone. It passes inferiorly between the internal and external carotid arteries. It then enters the pharyngeal wall between the superior and middle constrictors. It inserts into the posterior and lateral border of the thyroid cartilage.
Its actions are multiple:
elevate the larynx
elevate the pharynx
dilate the pharynx to permit the passage of a large food bolus, so facilitating swallowing
Stylopharyngeus is innervated by the muscular branch of the glossopharyngeal nerve (IX).
cheif sensory nucleus
what does it do?
Chief Sensory Nucleus receives and relays Fine (discriminative) orofacial touch sensations
Facial Nerve
general sensory functions
Tactile sensations from
- skin of external ear,
- wall of external auditory meatus
- outer surface of tympanic membrane
What gives the trochlear nerve its name?
The superior oblique muscle passes through a ligamentous ring called the trochlea
(the trochlear nerve innervates this muscle)
Glossopharyngeal nerve: where are the superior and inferior ganglia found?
the jugular foramen
Clinical Evaluation of the Facial Nerve: branchial motor
Ask patient to make Make facial expressions
- –Observe for asymmetries
as you see here with this woman is asked to smile and has left facial nerve palsy
Trigeminal nerve V: ascending tracts: The paramedial ascending system involves projcetctions
from where?
to where?
function
Projections from:
- chief sensory and
- spinal trigeminal nuclei
projcetions to:
- midline thalamus &
- into limbic system.
projections represent the Emotional response to facial touch or pain
superior oblique
Innervation:
primary action:
Innervation: Trochlear (IV)
primary action: intorsion
how many regions does the spinal trigeminal nucleus have?
three
§Oralis
§Interpolaris
§Caudalis
what is true about the three ascending tracts of the Trigeminal nerve?
All are decussated secondary axons from trigeminal relay nuclei
Glossopharyngeal nerve (IX): otic ganglion contains what kind of cell bodies?
–Otic ganglion –
parasympathetic efferents (the parasympathetic relay ganglion for the autonomic innervation of the parotid gland)
How does the accessory nerve cross in/out of cranium?
The Cervical ventral roots rise through the foramen magnum to join with the cranial portion.
Together both portions exits thru jugular foramen
Nuclei associated with Vestibulochochlear Nerve (6)
The Nuclei are located dorsal caudal pons & rostral medulla (very lateral)
There are two pairs of cochlear nuclei (on each side of the brainstem along the very lateral aspect of the rostral medulla)
- dorsal cochlear
- ventral cochlear
–there are four pairs of vestibular nuclei (which span the pontomedullary junction)
- lateral vestibular (not shown in picture)
- medial vestibular
- inferior vestibular
- superior vestibular (not shown in picture)
The nuclei of the 8th cranial nerve are located dorsal caudal pons & rostral medulla. There are a Pair of cochlear nuclei (dorsal and ventral) on each side of the brainstem along the very lateral aspect of the rostral medulla. These nuclei relay the auditory information. There are 4 pairs of vestibular nuclei: which span the pontomedullary junction named the Lateral, Medial, Inferior, and Superior nuclei
What types of functions can CN have? (3-4)
- ~motor ~somatosensory
- ~special sensor
- ~automatic components
(*CNs can have a single function or multiple functions)
where are the 2nd degree neurons for the sensory divisions of the trigeminal nerve? (3)
- Spinal trigeminal nucleus – (nucleus of the spinal tract of V)
- Chief (main) sensory nucleus
- Mesencephalic trigeminal nucleus
Four Disosrders of Eye Movement
- Opthalmoplegia – paralysis of one or more of the extraocular muscles
- Strabismus – inability to direct both eyes to the same object
- Lateral – due to paralysis of CN III
- Medial-due to paralysis of CN VI
- Diplopia – double vision
- Ptosis – weakness of levator palpebrae superioris muscle
what number is the vestibulocochlear nerve?
CN VIII
Edinger-Westphal nulceus:
what type of function?
What does it do?
(Part of the Oculomotor Nuclear Complex)
Visceral Motor
pre-ganglionic neurons for Parasympathetic axons to pupillary sphincter and ciliary body
- Puilary sphincter muscle produces pupillary constriction
- Activiation of the ciliary body produces accommodation of the lens for near vision
action of levator palpebrae superioris muscle:
raise eyelid
what is extorsion?
lateral rotation
Accessory Nerve Brahcnial motor innervates which muscles?
and which portions?
- –Sternocleidomastoid and upper trapezius muscles (cervical component)
- –Pharyngeal constrictors & laryngeal muscles (cranial component)
- with the vagus nerve
What does the maxillary nerve pass through when entering the scull?
foramen rotundum
what is the most common disorder of CN V?
Trigeminal Neuralgia (tic douloureux)
Facial Nerve
Somatic (branchial) Motor innervations:
- Muscles of facial expression &
- stapedius muscle
(associated nucleus: facial nucleus)
Where is the oculomotor nuclear complex?
Midbrain
Specifically the Dorsal Tegmentum just ventral to the periaqueductat gray.
Brainstem gaze centers:
Details on function
•Brainstem gaze centers
- –Regulate LMN activity in CN III, IV & VI nuclei
- Hortizontal gaze coordination in PPRF
- Vertical gaze in RIN
- Via medial longitudinal fasciculus (MLF) (from the brainstem nuclei to these lower motor nuclei are via MLF)
–These centers are in turn controlled by frontal eye fields of cerebral cortex
These Brainstem gaze centers Regulate LMN activity in CN III, IV & VI nuclei. It appears that Hortizontal gaze coordination is in the Paramedian pontine reticular formation (PPRF) and Vertical gaze is controlled in the Rostral interstitial nucleus. Connections from these brainstem nuclei to the oculomotor lower motor nuclei are via the ascending medial longitudinal fasciculus (MLF). Activity in these brainstem centers are in turn controlled by frontal eye fields of cerebral cortex. The whole story is more complicated than that and involves several brain regions (as illustrated in the lower picture) but we will not go into this topic in that detail. Suffice it to say that loss of conjugate eye movement can result from damage to more than one brain region.
What are in the Ventral Posteromedial nucleus of the thalamus?
3rd degree neurons of pathway that include the
- ascending V thalamic pahtway and
- ascending V lemniscal pathway
what does olfactory projections to the limbic structures do?
Limbic structures for strong emotional reactions to odors
Another name for the Spinal trigeminal nucleus
nucleus of the spinal tract of V
Oclulomotor nucleus:
UMN or LMN?
what type of function?
innervates what muscles? (5)
(Part of Oculomotor nuclear complex)
LMN with
somatic motor function
Innervates
- superior rectus
- medial rectus
- inferior rectus
- inferior oblique
- levator palpebrae muscle
How can the hypoglossal nerve be clinically evaluated? (3)
- •Observation of tongue protrusion with deviation toward affected side
- •Problems with speech articulation (dysarthria)
- •Atrophy of the tongue
Clinical examination of the hypoglossal nerve involves Observation of tongue protrusion with deviation toward affected side as seen in both the upper and lower pictures and Problems with speech articulation (dysarthria). Holding tongue “speech sounds something like this”. Also atrophy of the tongue is seen due to damage of the final common pathway to the skeletal muscle of the tongue as you can see in the lower picture
Nucleus interpolaris:
location
transmits
one of three regions of spinal trigeminal nucleus
- Mddle position
- Transmits
- Non-discriminative (crude) touch
- dental pain
Where does the asending V lemniscal pathway synapse with 3rd degree neurons? (after becoming the head region of the medial lemniscal tract)
Where do the 3rd degree neurons project?
synapse in Ventral Posteromedial thalamus (VPM)
projets onto face region along lateral somatosensory cortex
Name the 6 extraocular muscles:
and one related muscle
- Superior Rectus
- Inferior Rectus
- Medial Rectus
- Lateral Rectus
- Superior Oblique
- Inferior oblique
- Levator palpebrae superioris (eye lid)
where does the hypglossal nerve exit the cranium?
The hypoglossal nerve exits thru hypoglossal canal
name the functional types contained in the accessory nerve
somatic (branchial) motor
What does dorsal motor nucleus of vagus do for olfactory nerve signals?
nausea and vomiting to unpleasant odors
list the preipheral ganglia utilized by the vagus nerve:
- Superior ganglion – somatic afferents
- Inferior ganglion – visceral & special sensory afferents
- Terminal ganglia close to target tissues which are innervated by the vagus nerve are the parasympathetic efferents relay ganglia
What does the Mandibular nerve pass through when entering the scull?
foramen ovale
What provides cortical control of the msucles of mastication?
the descending corticobulbar fibers
(this will be discussed more in the future)
what happens with Abducens (CN VI) Opthalamoplegia? (2)
–Paresis/paralysis of lateral rectus
- –Eye moves medially due to unopposed action of the medial rectus
- –Head turned to affected side to reduce diplopia
Trochlear nucleus:
location
upper or lower motor nucleus?
What does fibers from it innervate?
in midbrain caudal to oculomotor complex
lower motor nucleus
innervates superior oblique
cranial nerve number of the vagus nerve
X
Herpes Zoster Ophthalmicus
prevalance
what happens?
another lesion of the Trigeminal nerve
- 10-15% of all cases of herpes zoster
- Inflammatory and infectious disease
- 2–3 days of severe pain along distribution of the opthalmic division (V1) of CN V
- Rash follows in this distribution
- Can result in permanent corneal damage
Herpes Zoster Ophthalmicus occurs in 10-15% of all cases of herpes zoster. It is a viral infectious disease accompanied by Inflammatory response around the nerve. It generally has the following symptoms 2–3 days of severe pain along distribution of the opthalmic division (V1) of CN V, Rash follows in this distribution and it can result in permanent corneal damage
MLF
Medial longitudinal fasciculus
Mesencephalic nucleus
location
what cell bodies are in it & purpose of those neurons?
in the midbrain and rostral pons
contains first degree afferent cell bodies for proprioceptive informatinon from the muscles of mastication - jaw position
(these primary afferents are the only CN V afferents that do not have their cell bodies in the trigeminal ganglion. This nucleus gives rise to our sensation of jaw position and is the afferent limb in reflexes like the jaw jerk reflex.)
list the functions of the branchial motor portion of the Vagus Nerve: (7)
Somatic motor (branchial) functions of the vagus nerve includes innervation of various pharyngeal and laryngeal muscles such as the following:
- –Pharyngeal constrictors
- –Cricothyroid
- –Instrinsic laryngeal muscles
- –Levator veli palatini
- –Palatopharyngeus
- –Palatoglossus
- –Musculus uvulae
name the functional categories of the trigeminal nerve
General sensory (head and face)
- –Opthalmic (V1)
- –Maxillary (V2)
- –Mandibular (V3)
Motor (muscles of mastication)
- Mandibular (V3) division
Palthway of the sensory (special & general) portion of facial nerve
–1st degree afferent cell bodies are in the geniculate ganglion (equivalent to Dorsal Root Ganglion)
–Synapse in appropriate nucleus
- General somantic in Nucleus of spinal tract of V
- special sensory in Gustatory nucleus (gustatory portion of the solitary nucleus)
The special and general sensory input have their primary afferent cell bodies in the geniculate ganglion (facial nerve equivalent to dorsal root ganglion) and then Synapse in appropriate CNS nucleus:
Nucleus of spinal tract of V for general somatic afference
Gustatory division of Solitary nucleus for the special sensory afferents of taste
Glossopharyngeal nerve: what type of neurons does the solitary nucleus have?
- afferent fibers from carotid bodies & carotid sinus whose cell bodies are in the inferior ganglion
- Gustatory division of solitary nucleus – which receives taste from posterior 1/3 of tongue and again has primary afferent inputs whose cell bodies are in the inferior ganglion
what CN number is the trochlear nerve?
IV
What does the Oculomotor nerve do?
Somatic Motor:
- Contracts the following muscles:
- Superior Rectus
- Medial Rectus
- Inferior Rectus
- Inferior oblique
- Levator palpebrae superioris
- Parasympathetic activation
- Pupillary constriction -pupillary sphincter
- Accommodation of the lens for near vision - ciliary body
What are the ganglia associated with the Glossopharyngeal nerve (IX)?
- –Superior ganglion –
- somatic afferents (cell bodies of somatic primary afferent fibers)
- –Inferior ganglion –
- visceral & special sensory (cell bodies of the visceral & special sensory primary afferent fibers)
- –Otic ganglion –
- parasympathetic efferents (the parasympathetic relay ganglion for the autonomic innervation of the parotid gland)
boxer puppy!
peek-a-boo!
What types of functions does the hypglossal nerve contain?
Purely somatic motor
- innervates the intrinsic & extrinsic toung muscles
Where does the asending V thalamic pathway synapse with 3rd degree neurons? (after becoming the head region of the anterolateral tracts)
Where do the 3rd degree neurons project?
synapse in Ventral Posteromedial thalamus (VPM)
projets onto face region along lateral somatosensory cortex
Four ways to clinically evaluate the Trigeminal Nerve:
- Corneal reflex
- Jaw Jerk reflex
- Sensory tests for fine touch and pin prick to the face
- Palpate usles of mastication, (have pt resist jaw opening during palpation)
Vagus Nerve: function of the superior ganglion
- Superior ganglion –
- somatic afferents
How can you clinically evaluate the vagus nerve? (3)
- The clinical evaluation of the vagus nerve begins with the Observation of movements of the soft palate when patient says “Ahh”.
- With a vagus nerve lesion there will be a Deviation of the uvula to the unaffected side.
- may also be a noticable Asymmetry of arch of soft palate on affected side
- •Observation of vocal quality
- –Lesions of CN X specifically recurrent laryngeal nerve can produce hoarseness of speech (dysarthria), inability to give voice (aphonia) or inspiratory stridor (high pitched sound during inspiration)
- •Difficulty with swallowing (dysphagia)
*
Facial nerve: What nucleus is associated with the somatic (branchial) motor functions
Facial nucleus
list the functions of the special sensory portion of the Vagus Nerve:
Special sensory functions include taste from taste receptors on the Epiglottis
How many genes code for olfactory receptors?
It is interesting to note that about 1,000 genes code for olfactory receptors – largest gene complex for any single purpose.
what kind of function does the trochlear nerve have?
Somatic Motor
list the functions of the general sensory portion of the Vagus Nerve: (5)
- –tactile sensations of the external ear
- –Pharynx & larynx
- –Cranial dura
- –Trachea & esophagus
- –Thoracic & abdominal viscera (from the viscera probably only pressure & pain)
list the functions of the visceral sensory portion of the Vagus Nerve:
Visceral sensory function includes afferents from
- atrial low pressure baroreceptors
- aortic high pressure baroreceptors
Vagus Nerve: function of the dorsal motor nucleus of X
–Dorsal motor nucleus of X –
visceral motor preganglionic parasympathetic efferents
Trigeminal Neuralgia (tic douloureux)
what is it?
what happens?
cause
)Most common disorder of CN V)
- Disease of PNS affecting the trigeminal ganglion or nerve
- No motor or sensory losses
- Excruciating bursts of pain, usually in one of the three sensory distributions of CN V
- No known cause but often triggered by use of jaw, yawning, hot and cold, light breeze on face
Lets talk about lesions to the trigeminal nerve. First Trigeminal Neuralgia (tic douloureux) is the Most common disorder of the trigeminal nerve. It is a condition of the PNS affecting the trigeminal ganglion or nerve. It involves Excruciating bursts of pain, usually in one of the three sensory distributions of CN V but with No motor or sensory losses. There is No known cause but often triggered by use of jaw, yawning, hot and cold, light breeze on face
Lateral rectus
Innervation
primary action
Innervation: Abducens (VI)
primary action: abduction
How do you test corneal reflex?
what is the afferent and efferent limbs?
- Touch cornea with wisp of cotton
- normal: produces blinking of the eye with V
- V is afferent limb & VII is the efferent limb
Superior rectus
Innervation:
primary action:
Innervation: Oculomotor (III)
primary action: elevation
What type of function does the olfacotry nerve have?
•Special sensory – sense of smell
Vagus Nerve: function of the nucleus ambiguus
–Nucleus ambiguus –
branchial motor to the pharyngeal and laryngeal musculature
Wallenberg’s syndrome
what is another name for it?
what causes it?
what charecterizes it?
- •Also called lateral medullary syndrome
- •Typically caused by a vascular lesion, occlusion of the posterior inferior cerebellar artery (PICA)
- •Characterized by loss of pain and thermal sense in ipsilateral face and contralateral body due to damage of ascending spinal trigeminal and STT tracts
Wallenberg’s Syndrome is a vascular condition also called lateral medullary syndrome. It is Typically caused by a vascular lesion, specifically occlusion of the posterior inferior cerebellar artery (PICA). Wallenberg’s Syndrome is Characterized by loss of pain and thermal sense in ipsilateral face and contralateral body due to damage of ascending spinal trigeminal axons and spinothalamic tracts because it affects the ascending Spinothalamic tracts that have already decussated and the spinal tract of V which carries axons which have not yet decussated
what nuclei serve the Glossopharyngeal Nerve (IX)?
- –Nucleus ambiguus –
- somatic motor
- –Inferior salivatory nucleus –
- parasympathetic preganglionics
- –Solitary nucleus –
- afferent fibers from carotid bodies & sinus
- Gustatory division of solitary nucleus serves taste from posterior 1/3 of tongue
- –Spinal trigeminal nucleus –
- sensation from tonsils, pharynx, middle ear & posterior 1/3 of the tongue
Facial Nerve
Special sensory functions
Taste information from the anterior 2/3 of the tounge
(associated nucleus: gustatory division of the solitary nucleus)
What controlls the activity in the PPRF and RIN brainstem centers that control conjugate eye movements?
Frontal Eye fields of cerebral cortex
Glossopharyngeal nerve: what type of neurons does the spinal trigeminal nucleus nucleus have?
Spinal trigeminal nucleus – receiving somatic sensation from tonsils, pharynx, middle ear & posterior 1/3 of the tongue and again has primary afferent input but whose cell bodies are in the superior ganglion
what happens with Trochlear (CN IV) Opthalamoplegia? (3)
–Paresis/paralysis of superior oblique
- Eye moves up & lateral
- Head tilt to unaffected side to reduce diplopia
- Diplopia again when looking downward as in reading & walking downstairs
Auditory Nerve:
where do nerve fibers end (I would say begin since it is sensory)?
where are cell bodies?
how does the nerve enter the cranium?
where does nerve enter brainstem?
- nerve Endings are in the cochlea
- found in the petrous portion of the temporal bone
- Cell bodies are in the spiral ganglion
- nerve Enters the cranium thru the internal acoustic meatus (so does vestibular nerve)
- nerve enters brainstem at pontomedulary junction (vestibular nerve does too)
Auditory nerve portion of the 8th Cranial nerve have their sensory endings in the organ of corti of the cochlea. The primary afferent axons have their Cell bodies in spiral ganglion and the nerve also enters the cranium thru internal acoustic meatus.
What is the purpose of the Somatic (Branchial motor) component of the glossopharyngeal nerve (IX)?
–Somatic (Branchial motor)- innervates stylopharyngeus muscle
chart of all the extraocular muscles, innervations and primary & secondary actions
We DO NOT need to know the secondary actions.
(I asked Dr. Lake in an email)
what is the CN number of the hypoglossal nerve?
XII
Movment of eyes to right requires the activation of which neurons?
Left oculomotor nucleus
right abducens nucleus
What is the purpose of the visceral sensory component of the glossopharyngeal nerve (IX)?
–Visceral sensory - fibers from the carotid bodies, carotid sinus
number for Accessory Nerve
XI
What nuclei and/or complexes serve the Oculomotor Nerve?
(CN III)
Oculomotor Nuclear Complex
- Oculomotor Nucleus
- Edinger-Westphal nucleus
Ascending V lemniscal pathway (tract):
origin
becomes
From the Chief sensory & nucleus oralis
Becomes the head region of the medial lemniscal tract
CN number for olfactory nerve:
I
what are the three division of the trigeminal nerve?
- –Opthalmic (V1)
- sensory
- –Maxillary (V2)
- sensory
- –Mandibular (V3)
- sensory
- motor
Does the trigeminal nerve have high or low innervation density?
What does the Ophthalmic nerve pass through when entering the scull?
Where does the vagus nerve exit the cranium?
the jugular foramen
How many pairs of CNs are there?
12
The Motor nucleus of V
location
contains
The Motor nucleus of V is
- Located in mid-pons just medial to the primary sensory nucleus of V and
- contains LMN to muscles of mastication & tensor tympani
Where does the control of the conjugate eye movement arise from?
Brainstem gaze centers located in
- Paramedian pontine reticular formation (PPRF) and the
- Rostral interstitial nucleus (RIN) of the midbrain reticular formation
Stapedius muscle
the smallest skeletal muscle in the human body. At just over one millimeter in length, its purpose is to stabilize the smallest bone in the body, the stapes in the inner ear.
innervated by the somatic (branchial) motor portion of the facial nerve
Vagus nerve: where are the superior and Inferior ganglia found?
jugular foramen
medial rectus
Innervation:
primary action:
Innervation: Oculomotor (III)
primary action: adduction
where is the abducens nucleus located?
caudal pons
what happens with Oculomotor (CN III) Opthalamoplegia? (3)
- –Lateral strabismus
- Unopposed lateral rectus (CN VI)
- –Ptosis
- Compensation with contract frontalis so raised eyebrow
- –Diplopia when looking downward
- Reading & walking downstairs
- Paresis or paralysis of inferior rectus on side of damage so only one eye will look down producing the double vision
name the three ascending tracts of teh trigeminal nerve
- –Lemniscal tract
- –Thalamic tract
- –Paramedial tract
What do superior & inferior salivatory nuclei do for olfactory nerve signals?
salivation to pleasant odors
where are the nuclei that serve the hypoglossal nerve located?
nuclei in the dorsal medulla
where is the primary olfactory cortex located?
what is an alternate name for it?
Primary olfactory cortex is located in the medial temporal lobe – pyriform area.
The pyriform cortex is composed of the:
- Periamygdaloid cortex
- Anterior portion of parahippocampal gyrus (entorhinal area)
Pyriform cortex is also called the entorhinal area (maybe or maybe it is only the anterior portion of the parahippocalmpal gyrus)
Book Said: Primary olfactory cortex consists of
- pyriform area - (it is found in anterior part of medial temporal lobe)
- cerebral cortex overlying the amygdala (also called periamygdaloid cortex)
- a restricted area of anterior parahipocampal gyrus (also called entorhinal area)
(in that case it doesn’t have an alternate name as the pyriform area is a seperate part of the primary olfactory cortex)
*I have submitted a question about this to Dr. Lake on the message board and will update the card when we get a response*
What can cause lesions of the accessory nerve?
•Lesions can occur with surgical procedures of the neck and with trauma
